You're free to disagree with me - the terms of the SLA are what matter; you can download/install the OS on any Mac running certain OS versions you own and control; installing it on someone else's is violating the SLA. And, you are trying to argue semantics re. the SLA is invoked when you install it - that is incorrect as well (see below: the license allows you to download, install, etc, etc), especially since the same terms apply to Lion, Mountain Lion, and Mavericks (which you have installed already).
Have you read the SLA? Here is an excerpt from the Yosemite SLA:
"Permitted License Uses and Restrictions.
A. Preinstalled and Single-Copy Apple Software License
Subject to the terms and conditions of this License, unless you obtained the Apple Software from the Mac App Store or under a volume license, maintenance or other written agreement from Apple, you are granted a limited, non-exclusive license to
install, use and run one (1) copy of the Apple Software on a single Apple-branded computer at any one time. For example, these single-copy license terms apply to you if you obtained the Apple Software reinstalled on Apple-branded hardware.
B. Mac App Store License
If you obtained a license for the Apple Software from the Mac App Store, then subject to the terms and conditions of this License and as permitted by the Mac App Store Usage Rules set forth in the App Store Terms and Conditions (http://www.apple.com/legal/internet-services/itunes/ww/) (“Usage Rules”), you are granted a limited, non-transferable, non-exclusive license:
ℹ to download, install, use and run for personal, non-commercial use, one (1) copy of the Apple Software directly on each Apple-branded computer running OS X Mavericks, OS X Mountain Lion, OS X Lion or OS X Snow Leopard (“Mac Computer”) that you own or control;"
and:
H. Other Use Restrictions
The grants set forth in this License do not permit you to, and you agree not to, install, use or run the Apple Software on any non-Apple-branded computer, or to enable others to do so. Except as otherwise permitted by the terms of this License or otherwise licensed by Apple: ℹ only one user may use the Apple Software at a time, and (ii) you may not make the Apple Software available over a network where it could be run or used by multiple computers at the same time. You may not rent, lease, lend, sell, redistribute or sublicense the Apple Software.
The above is in addition to the paragraphs I posted previously (regarding the fact that it is not transferable).
As I said, you can disagree with me, but you really cannot with the legal terms. And, there are terms for commercial settings; however, I do not know what they are as they are not available for viewing on the consumer site.